The present invention relates broadly to an underground mine roof drill dust collection system, and, in particular, to an improved three-stage dust collector.
In modern underground mining operations the method of supporting the mine roof by beams extending from floor to roof has been replaced by a method in which the roof is bolted to strata above the roof. Holes are drilled through the roof and into the supporting strata. Bolts are then utilized to secure the roof to the supporting strata. Large quantities of dust are generated in the roof drilling operation. It is desirable to move the generated dust from the roof drill operator environment. In addition to improving the operator environment, dust removal increases roof drill performance.
The prior art includes a three-stage roof drill dust collector developed by the assignee of the present application. This prior art three-stage collector is described in "Operation Manual for Donaldson Roof Drill Dust Collector RDXOO-4545" printed by the Donaldson Company, Inc. in 1975. The prior art dust collector described in this publication includes a first stage cyclone separator, a second stage separator, and a third stage filter. The second stage separator is a DONACLONE.RTM. Separator which includes reverse-flow cyclone separator tubes. The third stage is a single filter having a heavy-duty pleated paper cartridge. The dust particles are carried to the dust separator through a hollow drill rod and hose by a vacuum blower unit.
Periodically, the roof drilling operations must be stopped while the collected dust is removed from chambers within the three-stage dust collector. Additionally, as dust collects on the paper cartridge filter element, the air flow therethrough is restricted, and, therefore, the filter must be periodically cleaned and/or replaced. These operations increase the down time of the roof drill and increase the operator maintenance functions that must be completed. It is desirable, therefore, to increase the time between such maintenance operations while maintaining high dust collection efficiency and minimizing roof drill down time.
One such solution to the above problem could be to simply increase the size of the dust collection chambers and add additional filters to the third stage of the dust collector. However, this solution has the disadvantage that the size of the unit must be increased and to increase the unit's size and also maintain the dust collection efficiency of the prior art three-stage dust collector is not cost effective. Additionally, the maximum size of the three-stage dust collector housing is limited by the fact that it must be conveniently mounted on the roof-drill vehicle.
The present invention solves the problems associated with the prior art systems in that it provides a three-stage collector having the same if not better efficiency of the prior art collector, the same size housing of the prior art collector, and which increases the length of time between periodic operator maintenance. The advantages of the present invention are achieved through the utilization of a side outlet separator as the second stage of the three-stage collector as opposed to the prior art reverse flow cyclone tubes. The broad concept of a side outlet cyclone separator is disclosed and claimed in a co-pending patent application Ser. No. 794,045, filed May 5, 1977, assigned to the assignee of the present application. The side outlet cyclone separator utilized in the present invention combines the advantages of a high flow rate and efficiency present in straight-through axial cyclone separators with the non-scavenge flow characteristics acquired in reverse flow cyclone separators. The side outlet separator requires a smaller space within the three-stage collector than the prior art reverse flow separator, and, therefore, two third-stage filters can be utilized as opposed to the single filter of the prior art dust collector, It can be seen that by utilizing two filters as opposed to one, the time between cleaning or removal of the filter elements can be increased, minimizing operator maintenance.